[written]

You don't click because you're educated in these matters. Most people are not.

[daveFNbuck]

Not clicking on the credit card update e-mail requires being educated in these matters. Not clicking on the account verification e-mail just requires reading the e-mail before clicking. I think that's an important distinction.

[written]

Depends on the service. I've seen verification e-mails that just contain a link with no other text. Or with texts like "Continue here: [link]".